Nicaragua's Sandinista government says it is cracking down hard on civil liberties because it is threatened by U.S.-backed rebels. It also claims that the rebels lack popular support and are losing ground in battle. Both stories can't be true.

Clearly the Sandinistas are under severe pressure from the Reagan Administration, which wants their revolutionary government overthrown and is doing everything it can get away with to make that happen. Because there is little support in this country for a U.S. invasion of Nicaragua, President Reagan has hit at them indirectly, channeling money and supplies to rebel groups popularly known as contras. The contras have hurt the Nicaraguan economy and inflicted casualties on Sandinista security forces. But while they cause fear and chaos in Nicaragua, there is no evidence that the contras are about to topple the government.

In fact, the Sandinistas are a greater danger to themselves than are most of their opponents. Ardent young revolutionaries, they often overreact to criticism of their regime and their nationalistic brand of Marxism. In the last few years this wrath has focused on three sectors of Nicaraguan society: the free press, particularly the opposition newspaper La Prensa, the country's private businessmen and the Roman Catholic Church. With the decree announced last week, the heavy hand of government will fall on all Under the crackdown announced by President Daniel Ortega, the Sandinistas have suspended the rights of free expression, public assembly, unrestricted movement within the country and mail privacy. The government also suspended the right of labor unions to strike, the right to a speedy trial for criminal defendants and their right to appeal judicial sentences. The decree also gives police the authority to search homes and detain suspects without warrants.

Ortega said these totalitarian measures had to be taken because "the brutal aggression of North America and its internal allies has created an extraordinary situation." The official U.S. stance towards Nicaragua is aggressive and shortsighted. But in light of the fact that the Nicaraguan government has been easing the country's state-of-emergency laws ever since elections were held last year, with no apparent ill effects, such a sudden reversal of the policy cannot be justified or explained to anyone who lives in a real democracy.

The crackdown is bound to backfire on Ortega and his colleagues. At home it will cause more Nicaraguans to resent their heavy-handed government. Abroad it will lead not just the Sandinistas' critics but also their supporters to question whether the new Nicaraguan government has the popular support it claims. A genuinely popular government does not have to deprive its citizens of their most basic civil rights.